Vacuum still



H. E. ZAUGG July 15, 1958 VACUUM STILL Filed Oct. 21. 1955 w. N M e fife/d flalgg 4 QZQML/ 79 11 01729 United States Patent O VACUUM STILL Harold E. Zaugg, Waukegan, Ill., assignor to Abbott Erboratories, North Chicago, 111., a corporation of mots Application October 21, 1953, Serial No. 387,491

1 Claim. (Cl. 202-205) This invention relates to improvements in vacuum distillation apparatus and more particularly to a rotary type evaporative still.

Prior to this invention there has not been available to the chemist a still which can be readily employed for the rapid and efficient-distillation of intermediate quantities of say 5 to 50 grams of phlegmatic, non-crystalliable organic liquids. One type of molecularstill which is suitable for use in distilling small quantities of liquid has been disclosed in a co-pending application S. N. 248,194, filed September 25, 1951, by John Shavel, Jr. and Harold E. Zaugg. While this still is quite satisfactory for handling certain types of liquids, it is limited by the slow rate of distillation which is possible with this apparatus.

It is therefore a principal object of this invention to provide an evaporative still which is capable of handling small amounts of difficulty distillable liquids and which will provide relatively rapid distillation.

This object and many other objects and advantages of the invention will become apparent upon a consideration of the following description taken in conjunction with the accompanying drawings in which:

Figure 1 is a vertical, partially sectional view of .an improved evaporative still embodying the features of the invention, and Figure 2 is a detailed sectional view of a portion of the apparatus shown in Figure l and taken along the lines 2-2 of Figure 1.

According to the invention there is now provided a vacuum distillation apparatus which comprises a substantially cylindrical jacket which is adapted to be closed at one "end by abutting closure means. The

opposite end of the jacketris substantially spherical in shape and has a V-shaped distillate collecting depression at the bottom thereof. The bottom of the jacket slopes very gently from the open end towards the spherical end and a distillate discharging member is positioned at the bottom of the spherical end in communication with the distillate collecting depression in order to provide convenient discharge of distillate from the apparatus. Means is provided for evacuating the jacket and a vaporizing chamber of substantially cylindrical shape is positioned axially within said jacket. The vaporizing chamber is attached at one end to a shaft which is mounted for rotation on the closure means and the chamber is positioned in such a way that it can be axially rotated within the jacket. Radiant heating means is disposed externally of the jacket for heating the material to be distilled.

In a preferred embodiment of the invention it is desirable to also include an opening in the spherical end of the jacket through which a thermocouple well can be inserted into the open end of the rotating vaporizing chamber. It is also desirable to provide a dish shaped depression in the center of the vaporizing chamber n order that the last small quantity of material to be distilled will be collected in a position where the radiant heat may be concentrated on it.

2,843,535 Patented July 15, 1958 substantially V-shaped in cross section and which slopes downwardly. into a distillate delivery tube 15. Said delivery tube 15 consists of a standard taper ground glass joint 16 and a drip tip 17 which leads into a standard fraction cutter 18.

Near the top of the closed hemispherical end of the jacket 16 is sealed a socket 19 of a standard ball joint. A thermocouple well 29 is attached by means of a ring seal to the ball half 21 of the joint. At a point adjacent the closed end of the thermocouple well 20 the tube is bent as at 22 so as to parallel the surface of a rotating vaporizing chamber which will be described hereinafter.

Disposed within the jacket it] is a rotatable barrel or chamber 23 which comprises a glass cylinder 24 closed off square at one end 25 and having a constricted opening 26 at the other end. The opening 26 is formed by flanging the end of the cylinder 24 in and back with a heavy fused bead on the lip of the aperture. The middle portion of the cylinder 24 is flared out as at 27 to a larger external diameter than the remainder of the cylinder. This shallow well 27 provides a convenient spacefor accumulation of the last portion of distilland at a point where itwill be heated most efficiently and where it may be closely approached by the end 28 of the thermocouple .end 25 of the chamber 23 is fastenedwith litharge cement vorits equivalent, deposited in theannular space-between the end 25 and the cup 31.

The shaft 30 isheldby a chuck 32 which in turn is attached to a bearing sleeve 33. Also attached to the chuck 32 and extending beyond the bearing sleeve 33 is a splitbrass block 34. The end of this block 34is cutouttoaccommodate a magnet 35 which is *held in place by the set screw 36. The chuck and magnet assembly is sweated intoa double roll ball bearing 37 (Fig. 2) which must be adjusted to the point where it will turn easily with only a light oil such. as di-n-butyl phthalate or di-2-ethylhexyl phthalate as a lubricant. A housing 32% is provided for the shaft, magnet and bearing assembly and it is also convenient to provide several turns of a removable copper coil. 39 which may be used whenever cooling of the housing may be necessary. Another magnet 4t) is positioned very close to the end of the housing 38 and likewise in proximate relation to the magnet 35. The magnet 40 is mounted on the shaft 41 which in turn is actuated by the variable speed motor 42. It will be obvious that when the magnet 40 is rotated by the motor 42 the magnet 35 will be actuated and will result in turning the assembly, including the chamber 23. A source of radiant heat such as the infra-red lamp 43 is positioned externally of the jacket 10 and provides the necessary heat for distillation of the material contained within the chamber 23. More than one infra-red lamp may be used or if desired a Nichrome wire or coil may be employed as the source of infra-red heat.

In operating and assembling the apparatus the outer jacket 10 is fixed horizontally by clamping in the usual 3 fashion. The chamber 23 is attached to the chuck 32, and with the bearing unit, the housing and the coil is fitted to the ground flange 11 of the jacket 10. It is possible to manipulate the jacket in order to position it concentrically with the chamber 23 by merely slipping the ground flange 11 in relationship with the smooth face 44 of the housing 38. Prior to inserting the chamher 23 into the jacket 10 the distilland is charged into the chamber and after greasing the flanges 11 and 44 the unit is joined together by suitable clamping means. After the thermocouple well 20 and the fraction cutter 18 with suitable receivers (not shown) have been attached 'to the jacket 10, rotation of the external magnet 40 is begun. A fore-pump is started and, as the still is evacuated, the rotating chamber 23 is centered inside the jacket 10 by proper relative positioning of the two ground flanges 11 and 44. The infra-red heat source is brought up close to the jacket, and directed toward the center 27 of the chamber 23. If three lamps are used one is preferably placed directly under the depression 27 and the other two are placed at approximately 120 angles with it and with each other. In order to reduce heating of surrounding components to a minimum, shields are constructed of sheet aluminum (not shown) and are placed around the jacket 10 perpendicular to its longitudinal axis and on both sides of the heat lamps. The vaporizing chamber 23 is rotated at a desired speed by controlling the speed of the motor 42. As the chamber is rotated, the distilland wets the chamber wall, and a thin film adheres to the wall. In this manner a large surface area is exposed for evaporation and for heating by the externally disposed infra-red heat source. Vapors pass out through the constricted open end 26 of the chamber 23 p and are collected on the relatively cool surface of the spherical end of the jacket 10, and on other portions of the surface of the jacket 10. External cooling means may be applied to the jacket if desired. The distillate runs down into the trough 14 in the bottom of the jacket 10 and is delivered by way of the tube 15 into the fraction cutter 18 and into the receivers (not shown).

From the foregoing description of the apparatus it will be apparent that the invention now provides a very convenient apparatus for distilling small quantities of a difiicultly distillable material. Combined With the relatively high capacity of this unit is the simplicity thereof which results in an absolute minimum of flanges and openings through which a portion of the vacuum may be lost.

Others may use and adapt this invention to various uses by substituting obvious equivalents for the apparatus shown. It is considered that all such use and equivalents are covered by this invention, provided, however, that they fall within the scope of the appended claim.

I claim:

In a vacuum distillation apparatus comprising a substantially cylindrical, infra-red permeable jacket adapted to be closed at one end by abutting closure means, a planar outwardly facing flange on the open end of said jacket and adapted to abut a planar flange on said closure means, a closed end on said jacket, evacuating means for said jacket, a cylindrical vaporizing chamber closed at one end and axially disposed for rotation within said jacket, said chamber having an inwardly turned flange at the open end thereof, condensing means for converting vapors produced in said vaporizing chamber to a distillate, distillate receiving means associated with said jacket, magnetic means for rotating said chamber in response to a motor-driven magnet, and radiant heating means externally disposed of said jacket for heating said chamber; the improvements including a jacket wherein said closed end is spherical in structure and forms a stationary condensing surface, means in fluidtight association with said closed end of said jacket to allow introduction of a thermocouple therethrough, a distillate collecting depression adjacent the bottom of said jacket, a distillate discharging member communicating with said depression, a distillate receiving member in fluid-tight engagement with said discharging member, and said vaporizing chamber having a central portion of a larger internal diameter than the end portions whereby the distilland will be collected in the central portion.

References Cited in the file of this patent UNITED STATES PATENTS 440,752 Barotte Nov. 18, 1890 1,950,830 Dijck Mar. 13, 1934 2,129,596 Waterman et al. Sept. 6, 1938 2,180,050 Hickman Nov. 14, 1939 2,364,360 Hickman Dec. 5, 1944 2,538,967 Hickman Jan. 23, 1951 2,554,703 Hickman May 29, 1951 2,695,871 Shavel Nov. 30, 1954 FOREIGN PATENTS 614,388 Great Britain Dec. 15, 1948 OTHER REFERENCES Olive: Chemical Engineering Guide to Process Instrument Element, Part 2 Chemical Engineering, May 1952, McGraw-Hill, Section 1, Temperature.

Industrial and Eng. Chem., 1952, vol. 44, pages 1903-4. 

